JPH10186519A - Light source for projector - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve the illumination of a projected picture by bringing the shape of a luminous intensity distribution characteristic close to that of the display panel, thereby reducing the quantity of ineffective light reaching a part other than a display panel. SOLUTION: This light source for a projector 1 is formed so that a reflection mirror 3 is formed to such a shape that an ellipse appears in a section passing through the optical center line Z of the reflection mirror 3 and is formed as the ellipse whose long and short diameter directions are matched with the longitudinal and lateral directions of the display panel 11 in the shape when the reflection mirror 3 is viewed from the front side, and the second focus P2W of the ellipse appearing in the section on the side of the long diameter W is in a position further than the second focus P2H of the ellipse on the side of the short diameter H. Therefore, the shape of the luminous intensity distribution characteristic is brought close to that of the display panel. Thus, the quantity of the ineffective light reaching the part other than the display panel can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal projector, which displays a television image, a computer image, etc., on a liquid crystal display for displaying a matrix of an element size of 1 to 2 inches as a display panel. The present invention relates to a projector device for projecting a screen having a screen size of 50 to 200 inches, and more particularly to a light source for projection.

[0002]

2. Description of the Related Art FIG. 5 shows an example of the structure of a conventional light source for a projector of this type.
1, a reflecting mirror 92 having a spheroidal reflecting surface is integrally attached. The light source 91, that is, the arc of the metal halide lamp is made to coincide with the first focal point f1, the second focal point f2 is connected to the position of the projection lens 10, and the liquid crystal is placed in the optical path between the reflecting mirror 92 and the projection lens 10. The display panel 11 such as a display is located in advance.

[0003]

However, in the above-mentioned conventional projector light source 90, the reflecting mirror 9 is used.
Since 2 is formed as a spheroid, the cross-sectional shape of the projected light beam is also circular. For example, in order to irradiate the entire surface of the display panel 11 having an aspect ratio such as 9:16, as shown in FIG. In addition, the light distribution characteristic D must be set to a large irradiation circle (image circle), and the number of invalid portions reaching the outside of the display panel 11 increases, so that the luminous flux utilization rate decreases and the projected image becomes dark.

Further, as a general characteristic, in the reflection mirror 92 having a spheroidal surface, although a cross section of a circular light beam is obtained, the illuminance distribution tends to be concentrated at the center, whereby the light is projected on a screen or the like. The peripheral portion of an image becomes dark, and there is a problem that the image quality is degraded, and solving these points is an issue.

[0005]

According to the present invention, as a specific means for solving the above-mentioned conventional problems, a light source by a metal halide lamp and an appropriate convergence to the light from the light source are applied to a display panel. In a light source for a projector formed by causing this irradiation light to enter a projection lens, the reflecting mirror has a shape in which an ellipse appears in a cross section passing through the optical center line of the reflecting mirror, and the reflecting mirror is viewed from the front. The shape at the time is also formed as an ellipse in which the vertical and horizontal directions of the display panel coincide with the major axis and the minor axis direction, and the second focal point of the ellipse appearing in the cross section on the major axis side is the ellipse appearing in the cross section on the minor axis side. An object of the present invention is to solve the problem by providing a light source for a projector, wherein the light source is located farther than the second focus.

[0006]

Next, the present invention will be described in detail based on an embodiment shown in the drawings. 1 is a light source for a projector according to the present invention. The light source for a projector 1 includes a light source 2 which is, for example, a metal halide lamp and a reflecting mirror 3. This is the same as the conventional example in that the light is converged to irradiate the display panel 11 and the irradiated light is made incident on the projection lens 12.

In the present invention, the reflecting mirror 3 is formed as a compound ellipsoid instead of the conventional spheroid. In this embodiment, the reflecting mirror 3 has a frontal shape, that is, the display panel 11 side. The shape when viewed from the display panel 11
Is formed as an ellipse in which the vertical direction Y and the minor axis H direction match, and the horizontal side X direction and the major axis W direction match.

At this time, the light source 2, the reflecting mirror 3, the display panel 11, and the projection lens 12 are arranged on a straight line with their respective centers coincident with the optical center line Z. Are symmetrical in a cross section passing through the line optical center line Z.

At this time, in the present invention, an ellipse appears on the cross section of the reflecting mirror 3 passing through the line optical center line Z. Therefore, the ellipse appearing when cut along the minor axis H is The opening dimension of the opening is shorter than the ellipse appearing when cut along the major axis W, that is, the minor axis H <the major axis W.

The first focus of each ellipse appearing in each cross section is the position of the discharge arc when the light source 2 is a metal halide lamp, and the first focus when the light source 2 is an incandescent lamp such as a halogen lamp. Is set to the light emitting point P1 such as the position of the filament.

By making the first focal point coincide with the light emitting point P1 as described above, each ellipse appearing in each cross section converges light toward the second focal point P2. Here, in the present invention, the second focal point P2 of each ellipse
First, the second focal point P2H is set near the display panel 11 in the ellipse on the minor axis H side.

Further, in the ellipse of the major axis W, the second focal point P2W is set farther from the position of the second focal point P2H of the ellipse of the minor axis H, that is, closer to the projection lens 12, and the minor axis H The second focal point P2M of the ellipse appearing in the middle of the major axis W is
The second focus P2H and the second focus P2W are sequentially set at an intermediate position.

The setting of the above-mentioned second focal point P2 is not necessarily limited to the above-mentioned position. For example, referring to the illuminance distribution of the image actually projected on the screen by the projection lens 12, for example, the short diameter Second focus P of ellipse on H side
It is possible to freely change 2H to a position where an optimum result is obtained, such as near the projection lens 12.

However, in the present invention, the position of the second focal point P2W of the ellipse on the long diameter W side is set farther than the position of the second focal point P2H of the ellipse on the short diameter H side. By doing so, an optimum light distribution characteristic for the shape of the display panel 11 can be obtained as described later.

At this time, if the position of the second focal point P2 is set far, the light beam passes through the display panel 11 in a state where the convergence has not yet been sufficiently performed, and the passing position is also at the optical center. Since the light passes through a position distant from the line Z, it illuminates the periphery of the display panel 11.

FIG. 2 shows the light distribution characteristic D1 of the reflecting mirror 3 having the above configuration in comparison with the display panel 11. According to the present invention, the front shape of the reflecting mirror 3 is changed in the vertical direction Y of the display panel 11. And the minor axis H direction, the lateral side X direction and the major axis W direction are formed as an ellipse, and in addition, the second focal point P2 is set to the second focal point P2H <the second focal point P2W, so that the light distribution characteristic D
1 is also elliptical.

Therefore, the display panel 11 has a light distribution characteristic D
1, the front shape of the reflecting mirror 3 and the second focal point P
If the position 2 is set, compared to the case where the display panel 11 is illuminated with the circular light distribution characteristic of the conventional spheroid,
Efficient display panel 11 with reduced ineffective light quantity
Is possible, in other words, it is possible to obtain a brighter projected image.

FIG. 3 shows another embodiment of the present invention, in which the previous embodiment is set by paying attention to the dimensional ratio between the vertical side Y and the horizontal side X of the display panel 11. On the other hand, in this embodiment, the front shape of the reflecting mirror 4 is set by paying attention to the dimensional ratio of the diagonal line C of the display panel 11.

That is, in the rectangular display panel 11, since the relationship of vertical side Y <horizontal side X <diagonal line C is satisfied, the light distribution characteristic D1 only has an elliptical shape as in the previous embodiment. It is expected that a part of the peripheral light quantity will be insufficient in the diagonal direction C of the display panel 11.

Therefore, in this embodiment, in addition to the same reflecting mirror body 4a as described in the previous embodiment,
The auxiliary reflecting surface 4b is provided along the diagonal line C. At this time, the opening dimension T of the opening of the auxiliary reflecting surface 4b is set to be larger than the major diameter W of the reflecting mirror body 4a.

At this time, the auxiliary reflecting surface 4b has an ellipse in the cross section passing through the optical center line Z as in the other portions, and its first focal point is set at the light emitting point P1. The second focal point P2T is set at the same position as the second focal point P2W on the major axis W side of the reflecting mirror body 4a or farther than that.

By forming in this manner, the light distribution characteristic D2 of the reflecting mirror 4 has a shape in which diagonal projections are formed in the diagonal direction C of the display panel 11 as shown in FIG. Sufficient light quantity can be distributed also in the diagonal direction C where the distance from the center becomes the longest and the peripheral light quantity tends to be insufficient.

Here, the operation and effect of the above configuration will be concretely shown based on the results of trial manufacture and examination for realizing the present invention. When the display panel 11 is projected on a 40-inch screen, The average illuminance of the projected image is improved by 25% from 5576 lux to 6977 lux, and particularly from 4395 lux to 58
It improves by 32% to 11 looks, and the uniformity of the illuminance of the projected image is remarkable.

[0024]

As described above, according to the present invention, the reflecting mirror has a shape in which an ellipse appears in a section passing through the optical center line of the reflecting mirror, and the shape of the reflecting mirror when viewed from the front. Also, the vertical and horizontal directions of the display panel and the major axis, the minor axis direction is formed as an ellipse coincident, the second focal point of the ellipse appearing in the cross section on the major axis side than the second focal point of the ellipse appearing in the cross section on the minor axis side. The light source for the projector, which is located far away, also brings the shape of the light distribution characteristics closer to the shape of the display panel, thereby reducing the amount of invalid light reaching parts other than the display panel, and reducing the illuminance of the projected image. This has an extremely excellent effect on the improvement of.

Also, by changing the position of the second focal point so as to be distant on the long side of the display panel, it is possible to irradiate the peripheral portion on the long side of the display panel, which is located away from the optical center line. By improving the peripheral light amount, the illuminance distribution of the projected image is made uniform, and the effect of improving the quality of the projected image is also obtained.

Further, at a position substantially corresponding to a diagonal line of the display panel of the reflecting mirror, an auxiliary reflecting surface is provided in which the aperture diameter is partially set to be large and the second focal point of the ellipse at this portion is located far. This makes it possible to distribute the amount of light in the diagonal direction, in particular, where the illuminance is likely to be insufficient, thereby making the illuminance distribution of the projected image uniform and achieving an excellent effect of further improving the quality of the projected image.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an embodiment of a projector light source according to the present invention.

FIG. 2 is an explanatory diagram showing light distribution characteristics of the same embodiment.

FIG. 3 is a schematic perspective view showing another embodiment of the projector light source according to the present invention.

FIG. 4 is an explanatory diagram showing light distribution characteristics of another embodiment.

FIG. 5 is a sectional view showing a conventional example.

FIG. 6 is an explanatory diagram showing light distribution characteristics of a conventional example.

[Explanation of symbols]

 Reference Signs List 1 light source for projector 2 light source 3, 4 reflecting mirror 4a reflecting mirror body 4b auxiliary reflecting mirror 11 display panel 12 projection lens Z optical center line H reflection Minor axis of mirror W: major axis of reflecting mirror X: short side of display panel Y: long side of display panel C: diagonal line of display panel D1, D2: light distribution characteristics

Claims (2)

[Claims] 1. A light source for a metal halide lamp and a light source for a projector which irradiates a display panel by appropriately converging light from the light source and irradiates the illuminating light to a projection lens, wherein the reflecting mirror is the reflecting mirror. A cross-section passing through the optical center line of the display panel has an ellipse shape, and the shape of the reflector when viewed from the front is also formed as an ellipse in which the vertical and horizontal directions of the display panel coincide with the major axis and minor axis directions. ,
A light source for a projector, wherein a second focal point of an ellipse appearing in the cross section on the longer diameter side is located farther than a second focal point of an ellipse appearing in the cross section on the shorter diameter side. 2. A large opening diameter is partially set at a position substantially corresponding to a diagonal line of the display panel of the reflecting mirror, and a second focal point of an ellipse appearing on the cross section of this portion is located on the major axis side. 2. The light source for a projector according to claim 1, further comprising an auxiliary reflection surface located at a position equal to or farther from the second focal point of the ellipse appearing in the cross section.